Event-related brain potentials (ERPs), event-related heart rate and concomitant performance indices are to be recorded from young children, adolescents and young adults. ERPs will be recorded during visual word and pictorial versions of the continuous recognition memory paradigm and during divided and selective attention paradigms using tone and phonemic stimuli. Since behavioral evidence suggests that encoding efficiency increases with age and that information processing of pictorial and visually presented verbal material may differ as a function of age, interactions for both behavioral and ERP indices between Group and Stimulus Material are expected in the memory paradigm. It is expected that "P300" amplitude and/or latency will reflect recognition accuracy in all age groups but that this effect will be smaller for young children whose memory performance is expected to be poorer than the two older age groups. The recording of heart rate in this paradigm may aid in determining whether the young child is hampered in memory performance by attentional deficits. EPR indices of selective and divided attention (i.e., "processing negativity" or Nd) should reflect the allocation of attentional resources and allow the charting of the maturation of processing resources across the proposed age range. ERPs will be recorded from 5 midline scalp placements and two pair of lateral placements in order to determine whether topographic and/or lateralized differences in ERP components and, by implication, their intracranial generators, differ systematically between the three age groups in these proposed studies. The ERPs and event-related heart rate will provide data on the development of the temporal course of memory processing and the timing of psychophysiological events during selective and divided attention. These data will be relevant to the study of the development of selective attention and memory, their physiological underpinnings, and to the study of abnormal brain-behavior relationships in children who are characterized by arrests in development.